Pacific Ocean as the greatest theater of bird migration

Date:
February 8, 2022
Source:
Royal Netherlands Institute for Sea Research
Summary:
With a surface larger than all the continents together, the
Pacific Ocean is the most extreme environment a migratory bird can
encounter. Yet there are several bird species that conquer this
enormous body of water almost routinely. Migratory bird researchers
now provide a synthesis of all the knowns, and especially the many
unknowns about the extreme performances of migratory birds such
as bar-tailed godwits, whimbrels and red knots, which fly over
the Pacific Ocean.



FULL STORY ==========================================================================
With a surface larger than all the continents together, the Pacific
Ocean is the most extreme environment a migratory bird can encounter. Yet
there are several bird species that conquer this enormous body of water
almost routinely.

In the latest issue of the scientific journal Ornithology, migratory bird researchers from the Netherlands, the United States and Canada provide
a synthesis of all the knowns, and especially the many unknowns about
the extreme performances of migratory birds such as bar-tailed godwits, whimbrels and red knots, which fly over the Pacific Ocean.


==========================================================================
More efficiently than thought The biggest unknown appears to be the
energy consumption of the birds. A bar- tailed godwit departing
from Alaska weighs more than a pound (485 g) on average. Once it
arrives in New Zealand, only 215 g of that remains. "When we start
calculating from the energy content of the fat burned and the assumed
air resistance of birds, it seems that a bar-tailed godwit can fly for
a maximum of 4 days at a time," lead author of the paper, migratory
bird researcher Theunis Piersma of NIOZ, Royal Netherlands Institute
for Sea Research and University of Groningen says. "The truth is, they
fly for an average of up to 9 days at a time. We know this from research
with satellite-tagged birds. We therefore must conclude that the birds
fly much more efficiently than what we calculate on the basis of known
flight properties." Meteorologists In addition to being efficient fliers, birds also appear to be good meteorologists; to the enormous surprise
of the meteorologists among the researchers. For example, birds adapt
their departure from the northern hemisphere to the weather systems they
will later encounter over the southern hemisphere. In addition to this meteorological knowledge, birds also have an 'internal GPS' and a map
of the vast ocean, according to the researchers.

Piersma: "There is no other way to explain how bar-tailed godwits
departing from Alaska, fly over the open ocean almost without land
marks, continuously adjusting for wind drift, and then arrive spot-on
in New Zealand 12,000 kilometers later." Affected habitat Departures
from wintering areas are also adjusted to changes that individual birds
have observed in previous years during migration. Piersma: "Bar-tailed
godwits flying from New Zealand to Alaska refuel in the Yellow Sea,
off the Chinese and Korean coasts. We have seen that individuals can
leave earlier the following year. This could very well be an adaptation
to the worsening food situation in the Yellow Sea. It is important
to note that this could therefore be an adjustment of individual
animals, in addition to an evolutionary process, where 'earlier
birds' have an evolutionary advantage over later ones." Warning The
overview of scientific knowledge on Pacific migrants is, in a sense,
a wish list of the researchers: what remains to be discovered? "At
the same time, it is also a warning," Piersma says. "Changes to the
habitat of migratory birds and certainly changes in climate can have
enormous consequences for the fragile balance during such an immense
endeavor as migrating across the Pacific." Unofficial world record
The world record holder for long-distance migration is a bar-tailed
godwit that departed Alaska on September 16, 2020 with a transmitter
on its back. The bird arrived in New Zealand eleven days later, after a
flight of a whopping 12,854 km. "We know that these severely emaciated
birds want only one thing after arrival: not to eat but to sleep," said Professor of Migratory Bird Ecology Theunis Piersma. "This is still
an unofficial record, though. Only when this achievement is recorded
in a peer reviewed scientific journal, does the record really count." ========================================================================== Story Source: Materials provided by Royal_Netherlands_Institute_for_Sea_Research. Note: Content may be edited
for style and length.


========================================================================== Related Multimedia:
* Pacific_routes_of_7_migrating_shore_birds ========================================================================== Journal Reference:
1. Theunis Piersma, Robert E Gill, Jr, Daniel R Ruthrauff,
Christopher G
Guglielmo, Jesse R Conklin, Colleen M Handel. The Pacific as
the world's greatest theater of bird migration: Extreme flights
spark questions about physiological capabilities, behavior,
and the evolution of migratory pathways. Ornithology, 2022 DOI:
10.1093/ornithology/ukab086 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/02/220208105251.htm
--- up 9 weeks, 3 days, 7 hours, 13 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1:317/3)